ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixix 



Rurally associates itself with the idea of the contemporaneous origin 

 of its distinctive phsenomena. The longitudinal faults run northerly 

 and southerly, and the transverse ones easterly and westerly, and 

 great numbers of them follow this direction with great accuracy. 

 The Lakes district presents an exception to this rule. It forms an an- 

 ticlinal elevation running nearly E. and W. and terminating on the 

 west in a regular apse. If we assume, as seems highly probable, 

 that the Lake valleys originated in great dislocations, the faults of 

 this district must be considered as diverging, round the apse, with 

 great regularity from a central point. I have elsewhere shown that 

 such a disposition is perfectly accordant with the contemporaneous 

 origin of tliese faults, of which I regard it, in fact, as the strongest 

 indication. 



I now proceed to examine the discontinuities of stratii&cation by 

 which we must determine the proximate periods of those movements 

 which have so disturbed the strata of these regions of Wales and the 

 north of England. 



It does not appear that any distinct geological horizon of discon- 

 tinuity in Wales has been detected, notwithstanding the accurate 

 researches of the Geological Survey, anterior to the period of the 

 Caradoc Sandstone. I am not aware even of partial discontinui- 

 ties before that epoch, which appears the more singular on account 

 of the enormous mass of contemporaneous igneous products among 

 the beds which constitute the Barmouth series. Nor, with the ex- 

 ception of particular localities, does the discordance between the beds 

 of the Caradoc and those on which they are superincumbent appear 

 to be considerable. It is manifested over the widest area in that 

 part of N. Wales where the upper beds of the Caradoc seem to gra- 

 dually overlap the lower formations in wrapping round the northern 

 end of the Berwyns, and in their north-western extension from that 

 locality. The greatest amount of discordance is exhibited about the 

 Longmynd, where the Caradoc beds are superimposed with great un- 

 conformity on the edges of the nearly vertical beds of the much older 

 rocks of that district. 



In the trap region of Carneddau, to the N.E. of Builth, one trans- 

 verse section of the Survey exhibits the beds of the Wenlock Shale 

 in conformity with those of the upper Llandeilo Flags, the whole 

 being disturbed together by the outbreak of trap ; and another sec- 

 tion shows beds of the Wenlock Shale in positions almost perpendi- 

 cular to Llandeilo beds, much lower in the series. In these sections 

 the Caradoc beds are wanting. When we pass out of this limited 

 Trappean locality towards the S.W., no appearance of any correspond- 

 ing discontinuity in the stratification has been observed. There is, 

 on the contrary, a remarkable conformity from the Lower Silurians 

 to the (]oal-measures inclusive, the only indication of non-conformity 

 being an extension, in some cases, of a superincumbent beyond a 

 subjacent formation, but without a greater difference in the inclina- 

 tion of the beds of the respective formations than would result 

 from that gradual depression which must have accompanied the long- 



